extmod/modlwip: Add stream protocol read method.

extmod/modlwip.c

@@ -878,6 +878,19 @@ STATIC mp_obj_t lwip_socket_setsockopt(mp_uint_t n_args, const mp_obj_t *args) {
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(lwip_socket_setsockopt_obj, 4, 4, lwip_socket_setsockopt);
 
+STATIC mp_uint_t lwip_socket_read(mp_obj_t self_in, void *buf, mp_uint_t size, int *errcode) {
+    lwip_socket_obj_t *socket = self_in;
+
+    switch (socket->type) {
+        case MOD_NETWORK_SOCK_STREAM:
+            return lwip_tcp_receive(socket, buf, size, errcode);
+        case MOD_NETWORK_SOCK_DGRAM:
+            return lwip_udp_receive(socket, buf, size, NULL, NULL, errcode);
+    }
+    // Unreachable
+    return MP_STREAM_ERROR;
+}
+
 STATIC const mp_map_elem_t lwip_socket_locals_dict_table[] = {
     { MP_OBJ_NEW_QSTR(MP_QSTR___del__), (mp_obj_t)&lwip_socket_close_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_close), (mp_obj_t)&lwip_socket_close_obj },
@@ -894,11 +907,17 @@ STATIC const mp_map_elem_t lwip_socket_locals_dict_table[] = {
 };
 STATIC MP_DEFINE_CONST_DICT(lwip_socket_locals_dict, lwip_socket_locals_dict_table);
 
+STATIC const mp_stream_p_t lwip_socket_stream_p = {
+    .read = lwip_socket_read,
+    //.write = lwip_socket_write,
+};
+
 STATIC const mp_obj_type_t lwip_socket_type = {
     { &mp_type_type },
     .name = MP_QSTR_socket,
     .print = lwip_socket_print,
     .make_new = lwip_socket_make_new,
+    .stream_p = &lwip_socket_stream_p,
     .locals_dict = (mp_obj_t)&lwip_socket_locals_dict,
 };